A sandwich-type rhodium polyoxotungstate with unprecedented tetrarhodium-oxo core Na12[(Rh4(μ3–O)2(H2O)2)(H2W9O33)2]·38H2O (1) was obtained by hydrothermal reaction of rhodium(II) acetate and sodium tungstate; crystal structure was determined by X-ray diffractometry and was confirmed by 183W NMR data; 1 is active in electrocatalytic water oxidation.